Resplandecen means 'to shine brightly' or 'to gleam'. It's a beautiful, poetic verb that goes beyond the more common word for 'shine' (brillar).
In the song, the artist sings about his lover's eyes, "Con sus ojitos que resplandecen al parpadear" (With her little eyes that gleam when she blinks). He uses this powerful word to capture the magical, radiant quality of her gaze, making it an incredibly romantic and memorable description.
This song is a passionate love letter to one specific woman. EmmaKings describes her as a "mujer hermosa, divina y preciosa" (a beautiful, divine, and precious woman) who is completely without comparison. He sees her as both "buena y mala" (good and bad), admitting she has the "trucos necesarios que controlan cada parte de mi ser" (necessary tricks that control every part of my being). He's totally captivated, realizing she is his entire life.
He details exactly how she affects him. Her "sonrisa tan coquetona me hace temblar" (flirty smile makes me tremble) and just her touch gives him goosebumps. He describes her as the "punto clave que controla mi piel" (key point that controls my skin) and the "mami chula que me hace enloquecer" (hot mama who drives me crazy). It all builds to a simple, direct declaration: "¡Literal tú eres mi todo!" (Literally, you are my everything!).